/***************************************************************************
 *   Copyright (C) 2008 by Lorenzo Mainardi 				   *
 *   lormayna@gmail.com 						   *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include "polynomial.h"


PolynomialValue eval(const PolynomialKey *key, const PolynomialValue *values, const int degree, const PolynomialKey xs){
	int i,j;
	PolynomialValue vy[DEGREE-1];
	for(i=0;i<degree;i++){
		vy[i] = values[i];
		for(j=i-1;j>=0; j--){
			PolynomialValue den = (key[i]-key[j])%PRIME;
			if(den==0){
				return DOUBLE_POINT;
			}
			vy[j] = vy[j+1]%PRIME + (((vy[j+1] - vy[j])*(xs - key[i]))%PRIME)/den;
		}
		return vy[0];
	}
}
